Why Can't Tesla Cars Have Solar Panels For Charging ?

The advantage of battery systems is that all excess power generated by the solar panels can be stored

And used to provide electricity for your home or electric vehicle if panels are not producing any energy during the night.

While the solar panels on your cars roof can never completely recharge your batteries, solar power from

other sources is an excellent way to fuel your electric car.

Solar-powered chargers operate off of solar power, and they also may be capable of providing electricity for traditional EV chargers

which are connected to required hardware inside of existing solar systems.

Going Off-Grid also allows for vehicle charging without electricity, 

so that you can charge the vehicle dynamically using

the surplus sun stored in the daytime hours, thus maximizing the amount of renewable solar power used for driving.

During daylight hours, EVs can be charged using sunlight, with the excess solar stored in the Teslas battery packs

which are also connected to the power grid, in case the electric vehicles are running out of juice.